#include<bits/stdc++.h>
#define L(i, j, k) for(int i = (j); i <= (k); ++i)
#define R(i, j, k) for(int i = (j); i >= (k); --i)
#define ll long long 
#define vi vector < int > 
#define sz(a) ((int) (a).size())
#define ll long long 
#define ull unsigned long long
#define me(a, x) memset(a, x, sizeof(a)) 
using namespace std;
const int N = 2007, mod = 998244353;
int qpow(int x, int y = mod - 2) {
	int res = 1;
	for(; y; x = (ll) x * x % mod, y >>= 1) if(y & 1) res = (ll) res * x % mod;
	return res;
}
ll cn, cm;
int n, m;
char s[N], t[N];
ll len[N], LST[N], pr[N];
mt19937_64 orz(time(0) ^ *new int);
void SLV() {
	L(j, 1, n) {
		char c = s[j];
		int lst = 0;
		R(k, m, 1) if(t[k] == c) {
			if(!lst) {
				int cur = k + 1, add = 0;
				L(z, 1, m - 1) {
					if(cur > m) cur = 1, add = 1;
					if(len[cur] > len[k] + add) 
						swap(len[cur], len[k]), len[cur] += add, len[k] -= add;
					++cur;
				}
				len[k] += 1;
			} else {
				L(cur, k + 1, lst) 
					if(len[cur] > len[k]) 
						swap(len[cur], len[k]);
			}
			lst = k;
		}
	}
}
ull hsh[N], F[N]; 
int W[N][N];
int main() {
	ios :: sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	cin >> cn >> cm;
//	cn = cm = 1000;
//	n = m = 10;
//	L(i, 1, n) s[i] = orz() % 3 + 'A';
//	L(i, 1, m) t[i] = orz() % 3 + 'A';
	cin >> (s + 1) >> (t + 1);
	n = strlen(s + 1);
	m = strlen(t + 1);
	L(i, 1, m) {
		hsh[i] = orz();
	}
	int cnt = min(1000LL, cn);
	L(o, 1, cnt) SLV();
	cn -= cnt;
	cnt = min(1000LL, cn);
	L(i, 1, m) pr[i] = len[i];
	L(o, 1, cnt) {
		L(i, 1, m) LST[i] = len[i];
		SLV();
		ull ret = 0;
		L(i, 1, m) ret += (len[i] - LST[i]) * hsh[i], W[o][i] = len[i] - LST[i];
		F[o] = ret;
	}
	int cyc = 0;
	L(i, 1, cnt) {
		int ok = 1;
		L(j, 1, cnt - i) ok &= F[j] == F[j + i];
		if(ok) {
			cyc = i;
			break;
		}
	}
	L(i, 1, m) len[i] = pr[i];
	L(i, 1, cyc) {
		ll P = (cn - i + cyc) / cyc;
		L(j, 1, m) len[j] += P * W[i][j];
	}
	ll ans = 0;
	L(i, 1, m) ans += min(len[i], cm);
	cout << ans << '\n';
	return 0;
}